Mjölnir

Mjölnir is one of the best-documented Norse symbols, attested in both text and archaeology. The Prose Edda tells how it was forged by the brother of the dwarf Brokkr, called Eitri in one manuscript of Snorri's Edda and Sindri in another, while Brokkr worked the bellows. It would never miss, never fail to return to the hand, and could shrink to hide in a shirt, but its handle came out too short: a fly, usually taken to be Loki, stung Brokkr until he let the bellows drop for a moment. Thor uses it to battle the giants who threaten gods and men.
It is also sacred, not only martial. In the Eddic poem Þrymskviða the hammer is brought in 'to hallow the bride' and laid in the supposed bride's lap. In Snorri's Gylfaginning Thor hallows Baldr's funeral pyre with it, and raises his slaughtered goats back to life by hallowing their hides. A wedding, a funeral and a revival: that is the blessing-role the sources record.
Archaeology confirms its reach: about 1,000 Thor's-hammer pendants have been found across Scandinavia and the Viking diaspora, many of them in women's graves. One from Købelev on Lolland in Denmark, found in 2014, is the only one with runes: hmar is, 'this is a hammer'. The surge in wearing them is widely read as a pagan response to the Christian cross worn by missionaries and converts.
What we cannot say is exactly what any given pendant 'meant' to its wearer, or how closely the pendant shapes matched the hammer of myth. The objects are certain; the beliefs behind each one are inferred.